A look at how President Barack Obama’s remarks about the Syrian civil war have evolved as evidence suggesting chemical weapons use by President Bashar Assad’s government has emerged:

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Aug. 20, 2012

“We have communicated in no uncertain terms with every player in the region, that that’s a red line for us, and that there would be enormous consequences if we start seeing movement on the chemical weapons front, or the use of chemical weapons. That would change my calculations significantly.” — Comments at the White House.

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March 20

“Once we establish the facts, I have made clear that the use of chemical weapons is a game changer.” — In a news conference with Israeli Prime Minister Benjamin Netanyahu. Obama said the U.S. was investigating reports that chemical weapons had been used and was “deeply skeptical” of the Syrian regime’s claim that the rebels were behind such an attack.

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April 26

“For the Syrian government to utilize chemical weapons on its people crosses a line that will change my calculus and how the United States approaches these issues.” — After U.S. officials declared that the Syrian government probably had used chemical weapons twice in March. Obama said more investigation was needed to find proof.

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May 3

“I do not foresee a scenario in which boots on the ground in Syria, American boots on the ground, would not only be good for America but also would be good for Syria.” — At a news conference, echoing reluctance in Congress toward sending in ground troops and stressing the importance of acting in coordination with other nations.

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May 7

“You suggested even in your question a perceived crossing of a red line …. We have evidence that there has been the use of chemical weapons inside of Syria but I don’t make decisions based on ‘perceived,’ and I can’t organize international coalitions around ‘perceived.’ We’ve tried that in the past, by the way, and it didn’t work out well.” — Answering a reporter’s question about Syria at a news conference.

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May 16

“There’s no magic formula for dealing with an extraordinarily violent and difficult situation like Syria’s …. I preserve the options of taking additional steps both diplomatic and military because those chemical weapons inside of Syria also threaten our security over the long term as well as our allies and friends and neighbors.” — At a news conference with Turkish Prime Minister Recep Tayyip Erdogan, who has publicly urged the U.S. to take further steps to hasten Assad’s departure.